The present invention relates to the field of heart pump and heart assist devices. Specifically the present invention is a heart pump which is used to assist a patient's heart thereby reducing the strain under which it works. The invention is a ventricular assist device of a unique and simple design.
The inventor knows of no prior art heart assist device (the device) which accomplishes the functions or has the structure of the invention disclosed herein. For example U.S. Pat. No. 2,954,738 (DiVette) shows both a flat diaphragm and a cylindrical diaphragm for pumping blood. The flat diaphragm is driven by a cam, and the cylindrical diaphragm is symmetrical. Other than that there is no similarity between DiVette and the invention disclosed by the applicant. Further, U.S. Pat. No. 4,167,046 (Portner) shows a bag to do the pumping and a plate 17 on either side which appears to be pushed inward symmetrically; please see FIG. 2 of the Portner patent. The plates 17 never quite touch and the deformation of the sack is low. The actuator is a solenoid 33 which is coupled by means of a spring. Neither the solenoid nor the spring are present in the applicant's device. U.S. Pat. No. 4,222,127 (Donachy) uses a blood sac which is compressed by a diaphragm. The diaphragm appears to be driven by alternate vacuum pluses and the pressure pluses from the control unit. None of the balanced driving structure that is in the applicant's device is shown in Donachy. U.S. Pat. No. 4,293,961 (Runge) shows a mechanism which has little in common with the applicant's invention and which is intended for heart by-pass operations only. U.S. Pat. No. 4,384,829 (Conley) shows a blood pumping bag and plates 15 which are similar to the applicant's invention. The plates are driven by levers, however, the pivots of the levers are fixed and are driven by solenoid coils. This is different from the applicant's invention. U.S. Pat. No. 4,488,099 (LaForge) shows what appears to be the same mechanism as disclosed in Conley but the emphasis in the patent is on the control of the speed, acceleration, etc. of the pumping stroke. U.S. Pat. No. 4,557,673 ( Chen) likewise shows a blood pumping bag and the plates 34 that compress it from the sides. Like the previous patents the plates are mounted on lever arm with fixed pivots and solenoid coils to drive them. The emphasis of Chem is on the formation of the sac itself. U.S. Pat. No. 4,457,673 (Conley) again shows substantially the same mechanism but the emphasis appears to be on the fact that the lever that actuates the pusher plate is in fact a long leaf spring, giving desirable characteristics to the pump motion. This is not the same as the applicant's invention. U.S. Pat. No. 4,565,497 (Miller) again shows a similar mechanism driven by solenoids and using levers which are springs. There are additional pre-load springs. There is no hint of the use of symmetrical motion, linear bearings, or cam followers. Further, there is no hint of the applicant's lever arms which are driven in a linear path at lower end to move the middle lever pivot up a slot to impart linear movement to the top end of the lever connected to the pusher plates.
Finally, the pumping action of the applicant's invention, unlike prior devices of a similar nature, does not pump blood through the heart in high pressure spurts but rather allows the pump stroke of the heart assist device to begin gradually in order to allow the valves of the device to be activated less forcefully.